Band stop filter structures and methods of forming and operating same

ABSTRACT

A filter structure including a ground plane wherein the ground plane is in a first metal layer of an integrated circuit (IC) package. The filter structure further includes a plate in a second metal layer of the IC package. The filter structure further includes a dielectric layer between the ground plane and the plate, wherein the ground plane, the dielectric layer, and the plate are thereby configured as a capacitive device. The filter structure further includes an inductive device in a third metal layer of the IC package, wherein the inductive device is electrically connected to the plate.

BACKGROUND

Integrated circuit (IC) packages are often used for applications inwhich power is distributed among one or more IC dies. Power is commonlyrouted to an IC die in an IC package through a post-passivationinterconnect (PPI) structure that includes multiple redistributionlayers (RDL).

As IC applications become increasingly complex and depend on increasingclock speeds and decreasing power supply voltages, sensitivity to noisesuch as simultaneous switching noise (SSN) and ground bounce noise (GBN)increases. Performance of filters used to suppress such noise issometimes gauged by an S21 parameter, also referred to as a transmissioncoefficient, which indicates the amount of power transmitted by thefilter at a given frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIGS. 1A and 1B are diagrams of a band stop filter structure, inaccordance with some embodiments.

FIG. 2 is a diagram of a cross-sectional view of an IC package, inaccordance with some embodiments.

FIGS. 3A-3D are diagrams of band stop filter structures, in accordancewith some embodiments.

FIGS. 4A and 4B are diagrams of band stop filter structures, inaccordance with some embodiments.

FIG. 5 is a diagram of an inductive device, in accordance with someembodiments.

FIGS. 6A-6C are plots of band stop filter structure parameters, inaccordance with some embodiments.

FIG. 7 is a flowchart of a method of forming a band stop filterstructure, in accordance with some embodiments.

FIG. 8 is a flowchart of a method of filtering a signal, in accordancewith some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components, values, operations, materials,arrangements, or the like, are described below to simplify the presentdisclosure. These are, of course, merely examples and are not intendedto be limiting. Other components, values, operations, materials,arrangements, or the like, are contemplated. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

In various embodiments, a band stop filter structure includes a groundplane in a first metal layer of an IC package, a plate in a second metallayer of the IC package, and a dielectric layer between the ground planeand the plate, thereby forming a capacitive device. An inductive devicein a third metal layer of the IC package is electrically connected tothe plate, and the resultant LC circuit functions to reduce a highfrequency noise component of a signal transmitted from a first terminalof the filter structure to a second terminal of the filter structure.Compared to other approaches, e.g., printed circuit board (PCB) filters,the disclosed embodiments occupy less area and avoid additionalprocessing steps that increase manufacturing costs.

FIGS. 1A and 1B are diagrams of a band stop filter structure 100, inaccordance with some embodiments. FIG. 1A is a diagram based on a planview of band stop filter structure 100, and FIG. 1B is a diagram basedon a cross-sectional view of band stop filter structure 100 along theplane indicated by line A-A′ in FIG. 1A. In addition to band stop filter100, FIG. 1A depicts directions X and Y, and FIG. 1B depicts directionsX and Z.

Band stop filter structure 100 is a component of an IC package. In someembodiments, band stop filter structure 100 is part of a powerdistribution path among one or more of IC package dies, IC packageinterconnects, or IC package bump structures. In some embodiments, oneor more band stop filter structures 100 are part of an IC package 200,discussed below with respect to FIG. 2.

In some embodiments, band stop filter structure 100 is a component of a2.5D IC package. In some embodiments, band stop filter structure 100 isa component of a 3D IC package. In some embodiments, band stop filterstructure 100 is a component of an integrated fan-out (InFO) package. Insome embodiments, band stop filter structure 100 is one band stop filterstructure of a plurality of band stop filter structures in an ICpackage.

Band stop filter structure 100 includes a unit cell 100A and a unit cell100B. Unit cell 100A includes an inductive device 110A, a plate 120A,and a ground plane portion 130A. Inductive device 110A is positioned ina metal layer ML3 of the IC package, has a perimeter 110AP, overliesplate 120A, and is electrically connected to plate 120A by a via 115Athrough a dielectric layer DL2 of the IC package. Plate 120A ispositioned in a metal layer ML2 of the IC package, has a perimeter120AP, overlies ground plane portion 130A, and is electrically isolatedfrom ground plane portion 130A by a dielectric layer DL1 of the ICpackage. Ground plane portion 130A is a portion of a ground plane 130positioned in a metal layer ML1 of the IC package.

Plate 120A, ground plane portion 130A, and dielectric layer DL1 arethereby configured as a capacitive device 140A electrically connected toinductive device 110A through via 115A.

Unit cell 100B includes an inductive device 110B, a plate 120B, and aground plane portion 130B. Inductive device 110B is positioned in metallayer ML3, has a perimeter 110B, overlies plate 120B, and iselectrically connected to plate 120B by a via 115B through dielectriclayer DL2. Plate 120B is positioned in metal layer ML2, has a perimeter120B, overlies ground plane portion 130B, and is electrically isolatedfrom ground plane portion 130B by dielectric layer DL1. Ground planeportion 130B is a portion of ground plane 130.

Plate 120B, ground plane portion 130B, and dielectric layer DL1 arethereby configured as a capacitive device 140B electrically connected toinductive device 110B through via 115B.

Each of metal layers ML1, ML2, and ML3 is a metal layer of an ICpackage. In some embodiments, each of metal layers ML1, ML2, and ML3 isa metal redistribution layer of an IC package. In some embodiments, oneor more of metal layers ML1, ML2, or ML3 includes copper. In someembodiments, one or more of metal layers ML1, ML2, or ML3 includes aseed layer containing copper or a copper alloy. In some embodiments, oneor more of metal layers ML1, ML2, or ML3 includes a diffusion barrierlayer containing titanium.

In some embodiments, one or more of metal layers ML1, ML2, or ML3 has athickness (not labeled) ranging from 3 μm to 20 μm. In some embodiments,one or more of metal layers ML1, ML2, or ML3 has a thickness rangingfrom 5 μm to 10 μm. One or more of metal layers ML1, ML2, or ML3 havinga smaller thickness value reduces the ability of the one or more ofmetal layers ML1, ML2, or ML3 to provide desired electrical properties,e.g., conductivity, in some instances.

Each of dielectric layers DL1 and DL2 is an IC package layer includingone or more materials capable of providing physical separation and highelectrical resistance between one or more overlying package layers andone or more underlying package layers or an ambient environment. In someembodiments, one or both of dielectric layers DL1 and DL2 includes apolymer or another material suitable for physically and electricallyisolating one or more overlying package layers. In some embodiments, oneor both of dielectric layers DL1 and DL2 includes polybenzoxazole (PBO)or polyimide (PI).

In some embodiments, one or both of dielectric layers DL1 and DL2 has athickness (not labeled) ranging from 2 micrometers (μm) to 20 μm. Insome embodiments, one or both of dielectric layers DL1 and DL2 has athickness ranging from 4 μm to 10 μm. One or both of dielectric layersDL1 and DL2 having a smaller thickness value reduces the ability of theone or both of dielectric layers DL1 and DL2 to provide physical andelectrical isolation in some instances.

In some embodiments, one or both of dielectric layers DL1 and DL2 has adielectric constant ranging from 2 to 5. In some embodiments, one orboth of dielectric layers DL1 and DL2 has a dielectric constant rangingfrom 3 to 4.

Via 115A is a conductive structure in dielectric layer DL2 that overliesand contacts signal plate 120A, thereby being configured to provide anelectrical connection between inductive device 110A and plate 120A. Insome embodiments, via 115A includes a seed layer and/or a diffusionbarrier layer. In some embodiments, via 115A includes one or more metalssuch as copper, a copper alloy, aluminum, tungsten, and/or titanium.

In some embodiments, via 115A has a thickness (not labeled) that matchesthe thickness of dielectric layer DL2. In some embodiments, unit cell100A includes one or more layers (not shown) in addition to dielectriclayer DL2 between inductive device 110A and plate 120A, and via 115A hasa thickness greater than the thickness of dielectric layer DL2.

Inductive device 110A includes a terminal 110A1 and a terminal 110A2. Inthe embodiment depicted in FIGS. 1A and 1B, terminal 110A1 is a firstterminal of inductive device 110A, terminal 110A2 is a second terminalof inductive device 110A, and via 115A is a third terminal of inductivedevice 110A so that inductive device 110A is a three-terminal inductivedevice. In some embodiments, via 115A is electrically connected to oneof terminal 110A1 or terminal 110A2 so that inductive device 110A is atwo-terminal inductive device.

In the embodiment depicted in FIGS. 1A and 1B, inductive device 110Acomprises two paths 112A electrically connected at via 115A at a centerof inductive device 110A, the two paths 112A configured to provide apredetermined inductance between terminal 110A1 and via 115A and betweenterminal 110A2 and via 115A. In some embodiments, inductive device 110Ais inductive device 500, discussed below with respect to FIG. 5. In someembodiments, inductive device 110A comprises a configuration other thantwo paths 112A electrically connected at via 115A at a center ofinductive device 110A.

In the embodiment depicted in FIGS. 1A and 1B, perimeter 110AP isaligned with perimeter 120AP in the Z direction so that substantiallyall of inductive device 110A overlies substantially all of plate 120A.In some embodiments, perimeter 110AP is not aligned with perimeter 120APin the Z direction, and a portion or all of inductive device 110Aoverlies a portion of plate 120A. In some embodiments, perimeter 110APis not aligned with perimeter 120AP in the Z direction, and a portion ofinductive device 110A overlies a portion or all of plate 120A.

In the embodiment depicted in FIGS. 1A and 1B, perimeter 120AP ispositioned along the inside of perimeter 110AP. In some embodiments,perimeter 120AP is positioned directly below perimeter 110AP. In someembodiments, a portion of perimeter 120AP is positioned outside ofperimeter 110AP and a portion of perimeter 120AP is positioned inside ofperimeter 110AP.

Ground plane 130 has a perimeter 130P. In the embodiment depicted inFIGS. 1A and 1B, each of perimeter 110AP and 120AP is positioned alongthe inside of a portion of perimeter 130P. In some embodiments, one orboth of perimeter 110AP or perimeter 120AP is positioned directly abovea portion of perimeter 130P. In some embodiments, one or both ofperimeter 110AP or perimeter 120AP is positioned along the outside of aportion of perimeter 130P.

Plate 120A has a length L along the X direction and a height H along theY direction. An effective capacitance of capacitive device 140A isdetermined in part by values of length L and height H, and by a ratioL/H of length L to height H.

In some embodiments, one or both of length L or height H has a valueranging from 100 micrometers (μm) to 1000 μm. In some embodiments, oneor both of length L or height H has a value ranging from 300 μm to 600μm.

In some embodiments, ratio L/H has a value ranging from 0.8 to 1.2. Insome embodiments, ratio L/H has a value ranging from 0.9 to 1.1. In someembodiments, ratio L/H has a value approximately equal to 1.0.

In the embodiment depicted in FIGS. 1A and 1B, inductive device 110A,plate 120A, and ground plane portion 130A have a spatial relationship inwhich inductive device 110A, positioned in metal layer ML3, overliesplate 120A, positioned in metal layer ML2, and plate 120A overliesground plane portion 130A, positioned in metal layer ML1. In someembodiments, one or more of inductive device 110A, plate 120A, or groundplane portion 130A is positioned in a layer other than metal layers ML3,ML2, or ML1, respectively, such that inductive device 110A, plate 120A,and ground plane portion 130A have a spatial relationship that differsfrom that depicted in FIGS. 1A and 1B.

In some embodiments, inductive device 110A, plate 120A, and ground planeportion 130A have an inverted spatial relationship corresponding toground plane portion 130A being positioned in metal layer ML3, plate120A being positioned in metal layer ML2, and inductive structure 110Abeing positioned in metal layer ML1. In some embodiments, inductivedevice 110A, plate 120A, and ground plane portion 130A have a spatialrelationship corresponding to one of band stop filter structures 400A or400B, discussed below with respect to FIGS. 4A and 4B.

The elements of unit cell 100B are composed and configured in the mannerdiscussed above for the corresponding elements of unit cell 100A. Insome embodiments, unit cells 100A and 100B have a same configuration. Insome embodiments, unit cells 100A and 100B have configurations thatdiffer from each other.

In the embodiment depicted in FIGS. 1A and 1B, band stop filterstructure 100 includes two unit cells, unit cells 100A and 100B. In someembodiments, band stop filter structure 100 includes a single unit cell,and ground plane 130 includes only one of ground plane portions 130A or130B. In some embodiments, band stop filter structure 100 includesgreater than two unit cells and ground plane 130 includes one or moreground plane portions (not shown) in addition to ground plane portions130A and 130B.

In the embodiment depicted in FIGS. 1A and 1B, band stop filterstructure 100 includes unit cells 100A and 100B configured as a 1×2array of unit cells, i.e., one row and two columns. In some embodiments,band stop filter structure 100 includes unit cells 100A and 100B as partof an array of unit cells having more than two unit cells. In someembodiments, a unit cell, e.g., unit cell 100A, is one unit cell of anarray of unit cells 100A included in a band stop filter structure suchas one of band stop filter structures 300A-300D, discussed below withrespect to FIGS. 3A-3D.

Plates 120A and 120B are separated by a distance D along the Xdirection. A capacitive coupling between capacitive devices 140A and140B is determined in part by a value of distance D. In someembodiments, distance D is a minimum value of a manufacturing rule formetal layer ML2, in which each of plates 120A and 120B is positioned.

In some embodiments, distance D has a value ranging from 10 μm to 100μm. In some embodiments, distance D has a value ranging from 20 μm to 50μm. Distance D having larger values increases the area occupied by bandstop filter structure 100 in some instances.

In the embodiment depicted in FIGS. 1A and 1B, via 115A is positioned ata center of unit cell 100A, and via 115B is positioned at a center ofunit cell 100B. In some embodiments, one or both of vias 115A or 115B ispositioned at another location within the corresponding unit cell 100Aor 100B.

Inductive device 110B includes a terminal 110B1 and a terminal 110B2.Terminal 110A2 is electrically connected to terminal 110B1. In theembodiment depicted in FIGS. 1A and 1B, the entirety of inductivedevices 110A and 110B, including each of terminals 110A1, 110A2, 110B1,and 110B2, is positioned in metal layer ML3. In some embodiments,substantially all of inductive devices 110A and 110B is positioned inmetal layer ML3, and some or all of terminals 110A1, 110A2, 110B1, or110B2 is positioned in one or more metal layers (not shown) other thanmetal layer ML3.

In some embodiments, band stop filter structure 100, in operation,receives a signal at terminal 110A1, the signal comprising a powercomponent and a noise component. In some embodiments, the powercomponent is substantially a direct current (DC) signal and ispropagated through inductive device 110A from terminal 110A1 to terminal110A2, and through inductive device 110B from terminal 110B1 to terminal110B2. In some embodiments, the power component is substantially a lowfrequency alternating current (AC) signal and is propagated throughinductive device 110A from terminal 110A1 to terminal 110A2, and throughinductive device 110B from terminal 110B1 to terminal 110B2.

The noise component is substantially an AC signal including one or morehigh frequencies, e.g., a radio frequency (RF) and/or a microwavefrequency. In some embodiments, the noise component includes one or morefrequencies above 1 gigahertz (GHz). By the configuration depicted inFIGS. 1A and 1B, inductive device 110A and capacitive device 140A have afrequency response that, in operation, prevents a portion of the noisecomponent from propagating from terminal 110A1 to terminal 110A2 andinstead causes the portion of the noise component to propagate throughinductive device 110A and capacitive device 140A to ground plane 130.

By the configuration depicted in FIGS. 1A and 1B, inductive device 110Band capacitive device 140B have a frequency response that, in operation,prevents a further portion of the noise component from propagating fromterminal 110B1 to terminal 110B2 and instead causes the further portionof the noise component to propagate through inductive device 110B andcapacitive device 140B to ground plane 130.

By the configurations discussed above, band stop filter structure 100,compared to other noise filtering approaches, e.g., PCB filters,occupies less area and is capable of being formed without relying onadditional processing steps that increase manufacturing costs.

FIG. 2 is a diagram of a cross-sectional view of an IC package 200, inaccordance with some embodiments. IC package 200 includes bumpstructures 210P and 210G, power distribution paths 220P and 220G, bandstop filter structures 230 and 240, and IC dies 250 and 260. Band stopfilter structure 100, discussed above with respect to FIG. 1, is usableas one or both of band stop filters 230 or 240.

Power distribution path 220P is configured to provide an electricalconnection from bump structure 210P to each of IC dies 250 and 260, andpower distribution path 220G is configured to provide a groundconnection between bump structure 210G and each of IC dies 250 and 260.

Band stop filter structure 230 is part of power distribution path 220Pbetween bump structure 210P and IC die 250, and part of powerdistribution path 220G between bump structure 210G and IC die 250. Insome embodiments, band stop filter structure 100, discussed above withrespect to FIGS. 1A and 1B, is used as band stop filter structure 230,one or both of inductive devices 110A or 110B is part of powerdistribution path 220P, and ground plane 130 is part of powerdistribution path 220G.

Band stop filter structure 240 is part of power distribution path 220Pbetween IC die 250 and IC die 260, and part of power distribution path220G between IC die 250 and IC die 260. In some embodiments, band stopfilter structure 100, discussed above with respect to FIGS. 1A and 1B,is used as band stop filter structure 240, one or both of inductivedevices 110A or 110B is part of power distribution path 220P, and groundplane 130 is part of power distribution path 220G.

Bump structures 210P and 210G are conductive structures that overlie andcontact portions of power distribution paths 220P and 220G,respectively, thereby being configured to provide electrical connectionsbetween power distribution paths 220P and 220G and correspondingexternal conductive elements (not shown). In some embodiments, bumpstructures 210P and 210G include lead. In some embodiments, bumpstructures 210P and 210G include lead-free materials such as tin,nickel, gold, silver, copper, or other materials suitable for providingelectrical connections to external conductive elements.

In some embodiments, bump structures 210P and 210G have substantiallyspherical shapes. In some embodiments, bump structures 210P and 210G arecontrolled collapse chip connection (C4) bumps, ball grid array bumps,microbumps or the like.

Power distribution paths 220P and 220G are conductive structures in ICpackage 200. In some embodiments, power distribution paths 220P and 220Gare part of a PPI structure in IC package 200. In some embodiments,power distribution paths 220P and 220G are part of a power distributionnetwork within IC package 200. In some embodiments, IC package 200 isone IC package in a plurality of IC packages, and power distributionpaths 220P and 220G are part of a power distribution network within theplurality of IC packages.

Power distribution paths 220P and 220G include conductive and dielectricelements composed and configured in the manner of metal layers ML1, ML2,and ML3, dielectric layers DL1 and DL2, and vias 115A and 115B,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B.

By including one or more band stop filter structures 100, IC package200, compared to other approaches, e.g., IC packages including PCBfilters, is capable of filtering noise using one or more filters thatoccupies less area and is capable of being formed without relying onadditional processing steps that increase manufacturing costs.

FIGS. 3A-3D are diagrams of band stop filter structures 300A-300D, inaccordance with some embodiments. Each of band stop filter structures300A-300D includes an array of unit cells 100A, discussed above withrespect to band stop filter structure 100 and FIGS. 1A and 1B.

As depicted in FIG. 3A, band stop filter structure 300A includes a 1×4array of unit cells 100A, a terminal 300A1, and a terminal 300A2.Between terminals 300A1 and 300A2, each of four unit cells 100A in asingle row is electrically connected to an adjacent unit cell 100A by ashared terminal (not labeled).

In the manner discussed above with respect to band stop filter structure100 and FIGS. 1A and 1B, band stop filter structure 300A is therebyconfigured to, in operation, receive a signal at terminal 300A1,propagate a power component of the signal through inductive devices 110Ato terminal 300A2, prevent a portion of a noise component of the signalfrom propagating from terminal 300A1 to terminal 300A2, and insteadcause the portion of the noise component to propagate through inductivedevices 110A and capacitive devices 140A to ground plane 130.

By including four unit cells 100A, band stop filter structure 300A iscapable of propagating a larger portion of the noise component to groundin comparison to embodiments that include fewer than four unit cells,e.g., band stop filter structure 100 including unit cells 100A and 100B.

As depicted in FIG. 3B, band stop filter structure 300B includes a 1×8array of unit cells 100A, a terminal 300B1, and a terminal 300B2.Between terminals 300B1 and 300B2, each of eight unit cells 100A in asingle row is electrically connected to an adjacent unit cell 100A by ashared terminal (not labeled).

In the manner discussed above with respect to band stop filter structure100 and FIGS. 1A and 1B, band stop filter structure 300B is therebyconfigured to, in operation, receive a signal at terminal 300B1,propagate a power component of the signal through inductive devices 110Ato terminal 300B2, prevent a portion of a noise component of the signalfrom propagating from terminal 300B1 to terminal 300B2, and insteadcause the portion of the noise component to propagate through inductivedevices 110A and capacitive devices 140A to ground plane 130.

By including eight unit cells 100A, band stop filter structure 300B iscapable of propagating a larger portion of the noise component to groundin comparison to embodiments that include fewer than eight unit cells,e.g., band stop filter structure 100 including unit cells 100A and 100B.

As depicted in FIG. 3C, band stop filter structure 300C includes a 2×3array of unit cells 100A, a terminal 300C1, and a terminal 300C2.Between terminals 300C1 and 300C2, each of three unit cells 100A in eachof two rows is electrically connected to an adjacent unit cell 100A by ashared terminal (not labeled).

In the manner discussed above with respect to band stop filter structure100 and FIGS. 1A and 1B, band stop filter structure 300C is therebyconfigured to, in operation, receive a signal at terminal 300C1,propagate a power component of the signal through inductive devices 110Ato terminal 300C2, prevent a portion of a noise component of the signalfrom propagating from terminal 300C1 to terminal 300C2, and insteadcause the portion of the noise component to propagate through inductivedevices 110A and capacitive devices 140A to ground plane 130.

By including six unit cells 100A, band stop filter structure 300C iscapable of propagating a larger portion of the noise component to groundin comparison to embodiments that include fewer than six unit cells,e.g., band stop filter structure 100 including unit cells 100A and 100B.

As depicted in FIG. 3D, band stop filter structure 300D includes a 3×3array of unit cells 100A, a terminal 300D1, and a terminal 300D2.Between terminals 300D1 and 300D2, each of three unit cells 100A in eachof three rows is electrically connected to an adjacent unit cell 100A bya shared terminal (not labeled).

In the manner discussed above with respect to band stop filter structure100 and FIGS. 1A and 1B, band stop filter structure 300D is therebyconfigured to, in operation, receive a signal at terminal 300D1,propagate a power component of the signal through inductive devices 110Ato terminal 300D2, prevent a portion of a noise component of the signalfrom propagating from terminal 300D1 to terminal 300D2, and insteadcause the portion of the noise component to propagate through inductivedevices 110A and capacitive devices 140A to ground plane 130.

By including nine unit cells 100A, band stop filter structure 300C iscapable of propagating a larger portion of the noise component to groundin comparison to embodiments that include fewer than nine unit cells,e.g., band stop filter structure 100 including unit cells 100A and 100B.

By the configurations discussed above, each of band stop filterstructures 300A-300D, compared to other noise filtering approaches,e.g., PCB filters, occupies less area and is capable of being formedwithout relying on additional processing steps that increasemanufacturing costs.

FIGS. 4A and 4B are diagrams of band stop filter structures 400A and 4B,in accordance with some embodiments. Each of band stop filter structures400A and 400B includes features corresponding to inductive device 110A,via 115A, plate 120A, and ground plane portion 130A, discussed abovewith respect to unit cell 100A of band stop filter structure 100 andFIGS. 1A and 1B.

Band stop filter structure 400A (FIG. 4A) includes an inductive device410A, a conductive element 415A, a plate 420A, and a ground planeportion 430A. Inductive device 410A is positioned in metal layer ML3 andoverlies ground plane portion 430A, positioned in metal layer ML2, andground plane portion 430A overlies plate 420A, positioned in metal layerML1.

Conductive element 415A extends from inductive device 410A to plate420A, thereby providing an electrical connection between inductivedevice 410A and plate 420A. In some embodiments, conductive element 415Aextends through an opening in ground plane 430A. In some embodiments,conductive element 415A extends outside a perimeter of ground plane430A.

Ground plane 430A, dielectric layer DL1, and plate 420A are therebyconfigured as a capacitive device (not labeled) electrically connectedto inductive device 410A through conductive element 415A, and band stopfilter structure 400A is thereby configured as a unit cell having theproperties discussed above with respect to unit cell 100A of band stopfilter structure 100 and FIGS. 1A and 1B.

In some embodiments, the configuration of band stop filter structure400A causes band stop filter structure 400A to have properties thatdiffer from those of band stop filter structure 100 having similardimensions. For example, in some embodiments, conductive element 415Ahaving a length greater than a length of via 115A reduces an amount ofcoupling between inductive device 410A and the capacitive device formedby ground plane 430A, dielectric layer DL1, and plate 420A, as comparedto an amount of coupling between inductive device 110A and capacitivedevice 140A.

Band stop filter structure 400B (depicted in FIG. 4B) includes inductivedevices 410B1 and 410B2, conductive elements 415B1 and 415B2, plates420B1 and 420B2, and a ground plane portion 430B. Inductive device 410B1is positioned in a metal layer ML5 and overlies plate 420B1, positionedin a metal layer ML4, and plate 420B1 overlies ground plane portion430B, positioned in metal layer ML3. A dielectric layer DL4 ispositioned between metal layers ML5 and ML4, and a dielectric layer DL3is positioned between metal layers ML4 and ML3.

Conductive element 415B1 extends from inductive device 410B1 to plate420B1 through dielectric layer DL4, thereby providing an electricalconnection between inductive device 410B1 and plate 420B1. Plate 420B1,dielectric layer DL3, and ground plane portion 430B are configured as acapacitive device (not labeled) electrically connected to inductivedevice 410B1 through conductive element 415B1.

Ground plane portion 430B overlies plate 420B2, positioned in metallayer ML2, and plate 420B2 overlies inductive device 410B2, positionedin metal layer ML1. Ground plane 430B, dielectric layer DL2, and plate420B2 are thereby configured as a capacitive device (not labeled).Conductive element 415B2 extends from plate 420B2 to inductive device410B2 through dielectric layer DL1, thereby providing an electricalconnection between plate 420B2 and inductive device 410B2.

Band stop filter structure 400B is thereby configured as a first unitcell including inductive device 410B1, conductive element 415B1, plate420B1, and ground plane portion 430B, and a second unit cell includinginductive device 410B2, conductive element 415B2, plate 420B2, andground plane portion 430B, each unit cell having the propertiesdiscussed above with respect to unit cell 100A of band stop filterstructure 100 and FIGS. 1A and 1B.

In some embodiments, band stop filter 400B includes one or moreconductive elements (not shown) configured to provide an electricalconnection between inductive devices 410B1 and 410B2.

In some embodiments, band stop filter 400B band stop filter 400Bincludes one or more conductive elements configured to provide anelectrical connection between inductive devices 410B1 and 410B2, anddoes not include one of plates 420B1 or 420B2, so that band stop filter400B is configured as a single unit cell including inductive devices410B1 and 410B2 as a single, combined inductive device.

In some embodiments, the configuration of band stop filter structure400B causes band stop filter structure 400B to have properties thatdiffer from those of band stop filter structure 100 having similardimensions. For example, in some embodiments, dielectric layer DL3having a thickness larger than a thickness of dielectric layer DL1reduces a capacitance value of the capacitive device formed by plate420B1, dielectric layer DL3, and ground plane portion 430B, as comparedto a capacitance value of capacitive device 140A.

By the configurations discussed above, each of band stop filterstructures 400A and 400B, compared to other noise filtering approaches,e.g., PCB filters, occupies less area and is capable of being formedwithout relying on additional processing steps that increasemanufacturing costs.

FIG. 5 a diagram of an inductive device 500, in accordance with someembodiments. Inductive device 500 is usable as any of inductive devices110A or 110B, discussed above with respect to band stop filter structure100 and FIGS. 1A and 1B, inductive device 410A, discussed above withrespect to FIG. 4A, or inductive devices 410B1 or 410B2, discussed abovewith respect to FIG. 4B.

Inductive device 500 comprises two rotationally symmetrical spiralpaths, path 500P1 and path 500P2. Path 500P1 is an electricallyconductive path extending from a terminal 500T1 to a terminal 500T3positioned at the center of inductive device 500. Path 500P2 is anelectrically conductive path extending from a terminal 500T2 to terminal500T3. Paths 500P1 and 500P2 are thereby configured to provide apredetermined inductance between corresponding terminals 500T1 and500T3, and terminals 500T2 and 500T3.

In the embodiment depicted in FIG. 5, each of paths 500P1 and 500P2 hasthree vertical segments and four horizontal segments. In someembodiments, each of paths 500P1 and 500P2 has fewer than three verticalsegments and/or fewer than four horizontal segments. In someembodiments, each of paths 500P1 and 500P2 has greater than threevertical segments and/or greater than four horizontal segments.

Each of paths 500P1 and 500P2 has a width 500W, and paths 500P1 and500P2 are separated by a distance 500S. An effective inductance ofinductive device 500 is determined in part by a value of a ratio500S/500W.

In some embodiments, ratio 500S/500W has a value ranging from 1 to 2. Insome embodiments, ratio 500S/500W has a value ranging from 1.5 to 1.7.In some embodiments, ratio 500S/500W has a value approximately equal to1.6.

By including inductive device 500, a band stop filter structure,compared to other noise filtering approaches, e.g., PCB filters,occupies less area and is capable of being formed without relying onadditional processing steps that increase manufacturing costs.

FIGS. 6A-6C are plots of band stop filter structure parameters, inaccordance with some embodiments. FIGS. 6A-6C depict non-limitingexamples of values of the S21 parameter, also referred to as atransmission coefficient, which indicates the amount of powertransmitted by the filter at a given frequency. FIGS. 6A-6C depict thelogarithmic expression of the S21 parameter, given by:S21=20 log₁₀(b/a)  (1)where a represents input signal magnitude and b represents output signalmagnitude.

The non-limiting examples depicted in FIGS. 6A-6C are based onmeasurements of band stop filter structures 300A-300D, discussed abovewith respect to FIGS. 3A-3D, including inductive device 500, discussedabove with respect to FIG. 5. In each of FIGS. 6A-6C, S21 values areplotted along the y-axis, and frequency is plotted along the x-axis.

In the embodiments depicted in FIGS. 6A-6C, S21 parameter values areequivalent to S12 parameter values (representing the reverse directiontransmission coefficient) based on the reciprocal configuration of bandstop filter structures 300A-300D including inductive device 500. In someembodiments that do not include a reciprocal configuration, S21parameter values are not equivalent to S12 parameter values.

FIG. 6A depicts a plot of S21 values for embodiments of band stop filterstructure 300A corresponding to 1×4 arrays of square unit cells havingvarying sizes. Curve M2 depicts S21 values for a 1×4 array of unit cellshaving length L and height H equal to 300 μm, for which a resonancefrequency is 8.5 GHz. Curve M3 depicts S21 values for a 1×4 array ofunit cells having length L and height H equal to 400 μm, for which aresonance frequency is 4.7 GHz. Curve M4 depicts S21 values for a 1×4array of unit cells having length L and height H equal to 500 μm, forwhich a resonance frequency is 2.7 GHz. Curve M5 depicts S21 values fora 1×4 array of unit cells having length L and height H equal to 600 μm,for which a resonance frequency is 1.7 GHz.

Curves M2-M5 provide a non-limiting example of a relationship betweenunit cell size to resonance frequency, in which resonance frequencyincreases as unit cell size decreases.

FIG. 6B depicts a plot of S21 values for embodiments of band stop filterstructures 300A and 300B. Curve M6 depicts S21 values for an embodimentof band stop filter structure 300A corresponding to a 1×4 array ofsquare unit cells having length L and height H equal to 600 μm. Curve M7depicts S21 values for an embodiment of band stop filter structure 300Bcorresponding to a 1×8 array of square unit cells having length L andheight H equal to 600 μm.

Curves M6 and M7 provide a non-limiting example of a relationshipbetween unit cell array size and S21 values in which S21 values arelower for a 1×8 unit cell array than for a 1×4 unit cell array.

FIG. 6C depicts a plot of S21 values for embodiments of band stop filterstructures 300C and 300D. Curve M8 depicts S21 values for an embodimentof band stop filter structure 300C corresponding to a 2×3 array ofsquare unit cells having length L and height H equal to 500 μm. Curve M9depicts S21 values for an embodiment of band stop filter structure 300Dcorresponding to a 3×3 array of square unit cells having length L andheight H equal to 500 μm.

Curves M8 and M9 provide a non-limiting example of a relationshipbetween unit cell array size and S21 values in which S21 values arelower for a 3×3 unit cell array than for a 2×3 unit cell array.

FIG. 7 is a flowchart of a method 700 of forming a band stop filterstructure, in accordance with some embodiments. Method 700 is operableto form any of band stop filter structures 100, 300A-300C, 400A, or400B, discussed above with respect to FIGS. 1A, 1B, 3A-3C, 4A, and 4B.

In some embodiments, the operations of method 700 are performed in theorder depicted in FIG. 7. In some embodiments, the operations of method700 are performed in an order other than the order depicted in FIG. 7.In some embodiments, one or more additional operations are performedbefore, during, and/or after the operations of method 700.

In some embodiments, operations of method 700 are a subset of operationsof a method of forming an IC package. In some embodiments, theoperations of method 700 are a subset of operations of a method offorming a 2.5D IC package. In some embodiments, the operations of method700 are a subset of operations of a method of forming a 3D IC package.In some embodiments, the operations of method 700 are a subset ofoperations of a method of forming an InFO package. In some embodiments,the operations of method 700 are a subset of operations of a method offorming IC package 200, discussed above with respect to FIG. 2.

At operation 710, a ground plane is formed in a first PPI layer of an ICpackage. In some embodiments, forming the ground plane in the first PPIlayer of the IC package includes forming the ground plane in IC package200, discussed above with respect to FIG. 2.

In some embodiments, forming the ground plane in the first PPI layer ofthe IC package includes forming ground plane 130 in metal layer ML1,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B. In some embodiments, forming the ground plane in the firstPPI layer of the IC package includes forming ground plane 430A in metallayer ML2, discussed above with respect to band stop filter structure400A and FIG. 4A. In some embodiments, forming the ground plane in thefirst PPI layer of the IC package includes forming ground plane 430B inmetal layer ML3, discussed above with respect to band stop filterstructure 400B and FIG. 4B.

In some embodiments, forming the ground plane in the first PPI layer ofthe IC package includes forming one ground plane of a plurality ofground planes in the first PPI layer of the IC package.

In some embodiments, forming the ground plane in the first PPI layer ofthe IC package includes depositing a metal such as copper. In someembodiments, forming the ground plane in the first PPI layer of the ICpackage includes depositing a seed layer containing copper or a copperalloy. In some embodiments, forming the ground plane in the first PPIlayer of the IC package includes forming a diffusion barrier layercontaining titanium.

In some embodiments, forming the ground plane in the first PPI layer ofthe IC package includes depositing one or more materials through apatterned photoresist layer that is then removed. In some embodiments,forming the ground plane in the first PPI layer of the IC packageincludes performing one or more deposition processes followed byperforming one or more etching processes.

In some embodiments, forming the ground plane in the first PPI layer ofthe IC package includes forming the ground plane to a thickness rangingfrom 3 μm to 20 μm. In some embodiments, forming the ground plane in thefirst PPI layer of the IC package includes forming the ground plane to athickness ranging from 5 μm to 10 μm. Forming the ground plane to thethickness values discussed above enables the ground plane to provideelectrical conductivity and to be formed by processes consistent withone or more other IC package formation processes, thereby avoidingadditional processes that increase production costs in some instances.

At operation 720, a plate is formed in a second PPI layer of the ICpackage. In some embodiments, forming the plate in the second PPI layerof the IC package includes forming the plate in IC package 200,discussed above with respect to FIG. 2.

In some embodiments, forming the plate in the second PPI layer of the ICpackage includes forming one or both of plates 120A or 120B in metallayer ML2, discussed above with respect to band stop filter structure100 and FIGS. 1A and 1B.

In some embodiments, forming the plate in the second PPI layer of the ICpackage includes forming plate 420A in metal layer ML1, discussed abovewith respect to band stop filter structure 400A and FIG. 4A. In someembodiments, forming the plate in the second PPI layer of the IC packageincludes forming plate 420B1 in metal layer ML4, discussed above withrespect to band stop filter structure 400B and FIG. 4B. In someembodiments, forming the plate in the second PPI layer of the IC packageincludes forming plate 420B2 in metal layer ML2, discussed above withrespect to band stop filter structure 400B and FIG. 4B.

In some embodiments, forming the plate in the second PPI layer of the ICpackage includes forming one plate of a plurality of plates in thesecond PPI layer of the IC package. In some embodiments, forming theplate in the second PPI layer of the IC package includes forming oneplate of a plurality of plates in an array of unit cells of a band stopfilter structure. In some embodiments, forming the plate in the secondPPI layer of the IC package includes forming one plate of a plurality ofplates in an array of unit cells 100A of one of band stop filterstructures 300A-300D, discussed above with respect to FIGS. 3A-3D.

In some embodiments, forming the plate in the second PPI layer of the ICpackage includes depositing a metal such as copper. In some embodiments,forming the plate in the second PPI layer of the IC package includesdepositing a seed layer containing copper or a copper alloy. In someembodiments, forming the plate in the second PPI layer of the IC packageincludes forming a diffusion barrier layer containing titanium.

In some embodiments, forming the plate in the second PPI layer of the ICpackage includes depositing one or more materials through a patternedphotoresist layer that is then removed. In some embodiments, forming theplate in the second PPI layer of the IC package includes performing oneor more deposition processes followed by performing one or more etchingprocesses.

In some embodiments, forming the plate in the second PPI layer of the ICpackage includes forming the plate to a thickness ranging from 3 μm to20 μm. In some embodiments, forming the plate in the second PPI layer ofthe IC package includes forming the plate to a thickness ranging from 5μm to 10 μm. Forming the plate to the thickness values discussed aboveenables the plate to provide electrical conductivity and to be formed byprocesses consistent with one or more other IC package formationprocesses, thereby avoiding additional processes that increaseproduction costs in some instances.

At operation 730, a dielectric layer is deposited between the groundplane and the plate. In some embodiments, depositing the dielectriclayer between the ground plane and the plate includes depositing thedielectric layer in IC package 200, discussed above with respect to FIG.2.

In some embodiments, depositing the dielectric layer between the groundplane and the plate includes depositing dielectric layer DL1, discussedabove with respect to band stop filter structure 100 and FIGS. 1A and 1Band with respect to band stop filter structure 400A and FIG. 4A. In someembodiments, depositing the dielectric layer between the ground planeand the plate includes depositing dielectric layer DL3, discussed abovewith respect to band stop filter structure 400B and FIG. 4B. In someembodiments, depositing the dielectric layer between the ground planeand the plate includes depositing dielectric layer DL2, discussed abovewith respect to band stop filter structure 400B and FIG. 4B.

In some embodiments, depositing the dielectric layer between the groundplane and the plate includes depositing a polymer or another materialsuitable for physically and electrically isolating one or more overlyingpackage layers. In some embodiments, depositing the dielectric layerbetween the ground plane and the plate includes depositing PBO or PI.

In various embodiments, depositing the dielectric layer between theground plane and the plate includes performing a physical vapordeposition (PVD) or chemical vapor deposition (CVD) process, a laserchemical vapor deposition (LCVD) process, an evaporation process, anelectron beam evaporation (E-gun) process, or another suitabledeposition process.

In some embodiments, depositing the dielectric layer between the groundplane and the plate includes depositing the dielectric layer to have athickness ranging from 2 μm to 20 μm. In some embodiments, depositingthe dielectric layer between the ground plane and the plate includesdepositing the dielectric layer to have a thickness ranging from 4 μm to10 μm. Depositing the dielectric layer to have a smaller thickness valuereduces the ability of the dielectric layer to provide physical andelectrical isolation in some instances.

At operation 740, an inductive device is formed in a third PPI layer ofthe IC package. In some embodiments, forming the inductive device in thethird PPI layer of the IC package includes forming the inductive devicein IC package 200, discussed above with respect to FIG. 2.

In some embodiments, forming the inductive device in the third PPI layerof the IC package includes forming one or both of inductive devices 110Aor 110B in metal layer ML3, discussed above with respect to band stopfilter structure 100 and FIGS. 1A and 1B.

In some embodiments, forming the inductive device in the third PPI layerof the IC package includes forming inductive device 410A in metal layerML3, discussed above with respect to band stop filter structure 400A andFIG. 4A. In some embodiments, forming the inductive device in the thirdPPI layer of the IC package includes forming inductive device 410B1 inmetal layer ML5, discussed above with respect to band stop filterstructure 400B and FIG. 4B. In some embodiments, forming the inductivedevice in the third PPI layer of the IC package includes forminginductive device 410B2 in metal layer ML1, discussed above with respectto band stop filter structure 400B and FIG. 4B. In some embodiments,forming the inductive device in the third PPI layer of the IC packageincludes forming inductive device 500, discussed above with respect toFIG. 5.

In some embodiments, forming the inductive device in the third PPI layerof the IC package includes forming one inductive device of a pluralityof inductive devices in the third PPI layer of the IC package. In someembodiments, forming the inductive device in the third PPI layer of theIC package includes forming one inductive device of a plurality ofinductive devices in an array of unit cells of a band stop filterstructure. In some embodiments, forming the inductive device in thethird PPI layer of the IC package includes forming one inductive deviceof a plurality of inductive devices in an array of unit cells 100A ofone of band stop filter structures 300A-300D, discussed above withrespect to FIGS. 3A-3D.

In some embodiments, forming the inductive device in the third PPI layerof the IC package includes depositing a metal such as copper. In someembodiments, forming the inductive device in the third PPI layer of theIC package includes depositing a seed layer containing copper or acopper alloy. In some embodiments, forming the inductive device in thethird PPI layer of the IC package includes forming a diffusion barrierlayer containing titanium.

In some embodiments, forming the inductive device in the third PPI layerof the IC package includes depositing one or more materials through apatterned photoresist layer that is then removed. In some embodiments,forming the inductive device in the third PPI layer of the IC packageincludes performing one or more deposition processes followed byperforming one or more etching processes.

In some embodiments, forming the inductive device in the third PPI layerof the IC package includes forming the inductive device to a thicknessranging from 3 μm to 20 μm. In some embodiments, forming the inductivedevice in the third PPI layer of the IC package includes forming theinductive device to a thickness ranging from 5 μm to 10 μm. Forming theinductive device to the thickness values discussed above enables theinductive device to provide electrical conductivity and to be formed byprocesses consistent with one or more other IC package formationprocesses, thereby avoiding additional processes that increaseproduction costs in some instances.

At operation 750, an electrical connection is constructed between theplate and the inductive device. In some embodiments, constructing theelectrical connection between the plate and the inductive deviceincludes constructing the electrical connection in IC package 200,discussed above with respect to FIG. 2.

In some embodiments, constructing the electrical connection between theplate and the inductive device includes constructing a via between thesecond PPI layer and the third PPI layer. In some embodiments,constructing the electrical connection between the plate and theinductive device includes constructing one or both of vias 115A or 115Bin dielectric layer DL2, discussed above with respect to band stopfilter structure 100 and FIGS. 1A and 1B.

In some embodiments, constructing the electrical connection between theplate and the inductive device includes constructing conductive element415A in dielectric layers DL1 and DL2 and in metal layer ML2, discussedabove with respect to band stop filter structure 400A and FIG. 4A. Insome embodiments, constructing the electrical connection between theplate and the inductive device includes constructing conductive element415B1 in dielectric layer DL4, discussed above with respect to band stopfilter structure 400B and FIG. 4B. In some embodiments, constructing theelectrical connection between the plate and the inductive deviceincludes constructing conductive element 415B2 in dielectric layer DL1,discussed above with respect to band stop filter structure 400B and FIG.4B.

In some embodiments, constructing the electrical connection between theplate and the inductive device includes constructing one electricalconnection of a plurality of electrical connections between acorresponding plurality of plates and a corresponding plurality ofinductive devices. In some embodiments, constructing the electricalconnection between the plate and the inductive device includesconstructing one electrical connection of a plurality of electricalconnections in an array of unit cells of a band stop filter structure.In some embodiments, constructing the electrical connection between theplate and the inductive device includes constructing one electricalconnection of a plurality of electrical connections in an array of unitcells 100A of one of band stop filter structures 300A-300D, discussedabove with respect to FIGS. 3A-3D.

In some embodiments, constructing the electrical connection between theplate and the inductive device includes depositing copper. In someembodiments, constructing the electrical connection between the plateand the inductive device includes depositing a seed layer containingcopper or a copper alloy. In some embodiments, constructing theelectrical connection between the plate and the inductive deviceincludes depositing a diffusion barrier layer containing titanium.

In some embodiments, performing operations 720 and 740 includes forminga perimeter of the plate and a perimeter of the inductive device alignedin a direction perpendicular to a plane of the ground plane. In someembodiments, performing operations 720 and 740 includes forming one orboth of perimeters 110AP or 110BP aligned with corresponding one or bothof perimeters 120AP or 120BP in the Z direction, discussed above withrespect to band stop filter structure 100 and FIGS. 1A and 1B.

The operations of method 700 are capable of being performed as part of amethod of forming an IC package and are usable to form a band stopfilter structure that includes at least one L/C circuit, therebyobtaining the benefits discussed above with respect to band stop filterstructures 100, 300A-300D, 400A, and 400B.

FIG. 8 a flowchart of a method 800 of filtering a signal, in accordancewith some embodiments. Method 800 is usable with a band stop filterstructure, e.g., band stop filter structure 100 (FIGS. 1A and 1B), bandstop filter structures 300A-300D (FIGS. 3A-3D), or band stop filterstructures 400A and 400B (FIGS. 4A and 4B), or with an IC package, e.g.,IC package 200, discussed above with respect to FIG. 2.

At operation 810, an input signal is received at a first terminal of afilter structure in an IC package. The input signal includes a lowfrequency component and a high frequency component.

In some embodiments, the low frequency component includes asubstantially DC signal. In some embodiments, the low frequencycomponent includes an AC signal having one or more frequency componentsbelow a predetermined frequency. In some embodiments, the predeterminedfrequency defining the low frequency component has a value ranging from100 hertz (Hz) to 100 megahertz (MHz). In some embodiments, thepredetermined frequency defining the low frequency component has a valueranging from 1000 Hz to 100 kilohertz (kHz).

The high frequency component is an AC signal including one or more highfrequency components above a predetermined frequency. In someembodiments, the predetermined frequency defining the high frequencycomponent has a value ranging from 100 MHz to 100 GHz. In someembodiments, the predetermined frequency defining the high frequencycomponent has a value ranging from 1 GHz to 10 GHz.

In some embodiments, the low frequency component is a power componentand/or the high frequency component is a noise component, as discussedabove with respect to band stop filter structure 100 and FIGS. 1A and1B.

In some embodiments, receiving the input signal at the first terminal ofthe filter structure includes receiving the input signal within ICpackage 200, discussed above with respect to FIG. 2. In someembodiments, receiving the input signal at the first terminal of thefilter structure includes receiving the input signal at terminal 110A1of inductive device 110A, discussed above with respect to band stopfilter structure 100 and FIGS. 1A and 1B. In some embodiments, receivingthe input signal at the first terminal of the filter structure includesreceiving the input signal at terminal 110B1 of inductive device 110B,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B.

In some embodiments, receiving the input signal at the first terminal ofthe filter structure includes receiving the input signal at terminal300A1 of band stop filter structure 300A, discussed above with respectto FIG. 3A. In some embodiments, receiving the input signal at the firstterminal of the filter structure includes receiving the input signal atterminal 300B1 of band stop filter structure 300B, discussed above withrespect to FIG. 3B. In some embodiments, receiving the input signal atthe first terminal of the filter structure includes receiving the inputsignal at terminal 300C1 of band stop filter structure 300C, discussedabove with respect to FIG. 3C. In some embodiments, receiving the inputsignal at the first terminal of the filter structure includes receivingthe input signal at terminal 300D1 of band stop filter structure 300D,discussed above with respect to FIG. 3D.

In some embodiments, receiving the input signal at the first terminal ofthe filter structure includes receiving the input signal at inductivedevice 410A, discussed above with respect to band stop filter structure400A and FIG. 4A. In some embodiments, receiving the input signal at thefirst terminal of the filter structure includes receiving the inputsignal at inductive device 410B1, discussed above with respect to bandstop filter structure 400B and FIG. 4B. In some embodiments, receivingthe input signal at the first terminal of the filter structure includesreceiving the input signal at inductive device 410B2, discussed abovewith respect to band stop filter structure 400B and FIG. 4B. In someembodiments, receiving the input signal at the first terminal of thefilter structure includes receiving the input signal at terminal 500T1of inductive device 500, discussed above with respect to FIG. 5.

At operation 820, the high frequency component of the input signal isreduced using the filter structure to generate an output signal. In someembodiments, reducing the high frequency component of the input signalincludes reducing a noise component, as discussed above with respect toband stop filter structure 100 and FIGS. 1A and 1B.

Reducing the high frequency component of the input signal using thefilter structure includes using the filter structure including aninductive device and a capacitive device. The inductive device islocated in a first metal layer of the IC package and the capacitivedevice is electrically connected to the inductive device. The capacitivedevice includes a first metal plate in a second metal layer of the ICpackage and a second metal plate in a third metal layer of the ICpackage.

In some embodiments, the inductive device and the capacitive device arelocated within IC package 200, and reducing the high frequency componentof the input signal includes reducing the high frequency component ofthe input signal within IC package 200, discussed above with respect toFIG. 2.

In some embodiments, reducing the high frequency component of the inputsignal includes using one or both of unit cells 100A or 100B, discussedabove with respect to band stop filter structure 100 and FIGS. 1A and1B.

In some embodiments, reducing the high frequency component of the inputsignal includes using one of band stop filter structures 300A-300D,discussed above with respect to FIGS. 3A-3D.

In some embodiments, reducing the high frequency component of the inputsignal includes using inductive device 110A, discussed above withrespect to band stop filter structure 100 and FIGS. 1A and 1B. In someembodiments, reducing the high frequency component of the input signalincludes using inductive device 110B, discussed above with respect toband stop filter structure 100 and FIGS. 1A and 1B.

In some embodiments, reducing the high frequency component of the inputsignal includes using inductive device 410A, discussed above withrespect to band stop filter structure 400A and FIG. 4A. In someembodiments, reducing the high frequency component of the input signalincludes using inductive device 410B1, discussed above with respect toband stop filter structure 400B and FIG. 4B. In some embodiments,reducing the high frequency component of the input signal includes usinginductive device 410B2, discussed above with respect to band stop filterstructure 400B and FIG. 4B. In some embodiments, reducing the highfrequency component of the input signal includes using inductive device500, discussed above with respect to FIG. 5.

In some embodiments, reducing the high frequency component of the inputsignal includes using one or both of capacitive devices 140A or 140B,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B.

In some embodiments, the capacitive device including the first plate inthe second metal layer of the IC package includes one or both ofcapacitive devices 140A or 140B including ground plane 130, discussedabove with respect to band stop filter structure 100 and FIGS. 1A and1B. In some embodiments, the capacitive device including the secondplate in the third metal layer of the IC package includes capacitivedevice 140A including plate 120A, discussed above with respect to bandstop filter structure 100 and FIGS. 1A and 1B. In some embodiments, thecapacitive device including the second plate in the third metal layer ofthe IC package includes capacitive device 140B including plate 120B,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B. In some embodiments, the capacitive device including thefirst plate in the second metal layer of the IC package includes thecapacitive device including plate 420A, discussed above with respect toband stop filter structure 400A and FIG. 4A. In some embodiments, thecapacitive device including the first plate in the second metal layer ofthe IC package includes the capacitive device including plate 420B1,discussed above with respect to band stop filter structure 400B and FIG.4B. In some embodiments, the capacitive device including the first platein the second metal layer of the IC package includes the capacitivedevice including plate 420B2, discussed above with respect to band stopfilter structure 400B and FIG. 4B.

In some embodiments, the filter structure includes another inductivedevice in the first metal layer electrically connected to anothercapacitive device including the first plate and a third plate in thethird metal layer of the IC package.

In some embodiments, the filter structure including another inductivedevice includes the filter structure including inductive device 110B,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B. In some embodiments, the filter structure including anotherinductive device includes the filter structure including inductivedevice 410A, discussed above with respect to band stop filter structure400A and FIG. 4A. In some embodiments, the filter structure includinganother inductive device includes the filter structure including one ofinductive devices 410B1 or 410B2, discussed above with respect to bandstop filter structure 400B and FIG. 4B. In some embodiments, the filterstructure including another inductive device includes the filterstructure including inductive device 500, discussed above with respectto FIG. 5.

In some embodiments, the filter structure including another capacitivedevice includes the filter structure including capacitive device 140B,discussed above with respect to band stop filter structure 100 and FIGS.1A and 1B. In some embodiments, the another capacitive device includingthe third plate in the third metal layer of the IC package includescapacitive device 140B including plate 120B, discussed above withrespect to band stop filter structure 100 and FIGS. 1A and 1B.

In some embodiments, the another capacitive device including the thirdplate in the third metal layer of the IC package includes the capacitivedevice including plate 420A, discussed above with respect to band stopfilter structure 400A and FIG. 4A. In some embodiments, the anothercapacitive device including the third plate in the third metal layer ofthe IC package includes the capacitive device including one of plates420B1 or 420B2, discussed above with respect to band stop filterstructure 400B and FIG. 4B.

In some embodiments, the filter structure including an inductive deviceand a capacitive device includes the filter structure including a firstunit cell 100A, and the filter structure including another inductivedevice and another capacitive device includes the filter structureincluding a second unit cell 100A, discussed above with respect to bandstop filter structures 300A-300D and FIGS. 3A-3D.

In some embodiments, reducing the high frequency component of the inputsignal includes transmitting a remaining portion of the high frequencycomponent corresponding to a transmission coefficient. In someembodiments, reducing the high frequency component of the input signalincludes transmitting the remaining portion of the high frequencycomponent corresponding to transmission coefficients M2-M9, discussedabove with respect to FIGS. 6A-6C.

In some embodiments, reducing the high frequency component of the inputsignal includes reducing the high frequency component based on apredetermined resonance frequency corresponding to a size of theinductive device and a size of the capacitive device. In someembodiments, the predetermined resonance frequency is greater than 1GHz.

At operation 830, the output signal is provided at a second terminal ofthe filter structure. In some embodiments, providing the output signalat the second terminal of the filter structure includes providing theoutput signal within IC package 200, discussed above with respect toFIG. 2.

In some embodiments, providing the output signal at the second terminalof the filter structure includes providing the output signal at terminal110A2 of inductive device 110A, discussed above with respect to bandstop filter structure 100 and FIGS. 1A and 1B. In some embodiments,providing the output signal at the second terminal of the filterstructure includes providing the output signal at terminal 110B2 ofinductive device 110B, discussed above with respect to band stop filterstructure 100 and FIGS. 1A and 1B.

In some embodiments, providing the output signal at the second terminalof the filter structure includes providing the output signal at terminal300A2 of band stop filter structure 300A, discussed above with respectto FIG. 3A. In some embodiments, providing the output signal at thesecond terminal of the filter structure includes providing the outputsignal at terminal 300B2 of band stop filter structure 300B, discussedabove with respect to FIG. 3B. In some embodiments, providing the outputsignal at the second terminal of the filter structure includes providingthe output signal at terminal 300C2 of band stop filter structure 300C,discussed above with respect to FIG. 3C. In some embodiments, providingthe output signal at the second terminal of the filter structureincludes providing the output signal at terminal 300D2 of band stopfilter structure 300D, discussed above with respect to FIG. 3D.

In some embodiments, providing the output signal at the second terminalof the filter structure includes providing the output signal atinductive device 410A, discussed above with respect to band stop filterstructure 400A and FIG. 4A. In some embodiments, providing the outputsignal at the second terminal of the filter structure includes providingthe output signal at inductive device 410B1, discussed above withrespect to band stop filter structure 400B and FIG. 4B. In someembodiments, providing the output signal at the second terminal of thefilter structure includes providing the output signal at inductivedevice 410B2, discussed above with respect to band stop filter structure400B and FIG. 4B. In some embodiments, providing the output signal atthe second terminal of the filter structure includes providing theoutput signal at terminal 500T2 of inductive device 500, discussed abovewith respect to FIG. 5

By performing operations of method 800, a signal has a high frequencycomponent reduced between a first terminal and a second terminal of afilter structure in an IC package, the signal therefore beingcommunicated in accordance with the benefits discussed above withrespect to band stop filter structures 100, 300A-300D, 400A, and 400B.

One aspect of this description relates to a filter structure. The filterstructure includes a ground plane wherein the ground plane is in a firstmetal layer of an integrated circuit (IC) package. The filter structurefurther includes a plate in a second metal layer of the IC package. Thefilter structure further includes a dielectric layer between the groundplane and the plate, wherein the ground plane, the dielectric layer, andthe plate are thereby configured as a capacitive device. The filterstructure further includes an inductive device in a third metal layer ofthe IC package, wherein the inductive device is electrically connectedto the plate. In some embodiments, the plate is positioned between theground plane and the inductive device. In some embodiments, a perimeterof the plate is aligned with a perimeter of the inductive device. Insome embodiments, the inductive device includes two symmetrical spiralpaths electrically connected at a center of the inductive device. Insome embodiments, the filter structure further includes a via extendingfrom the center of the inductive device to the plate. In someembodiments, each path of the two symmetrical spiral paths has a widthw, the two symmetrical spiral paths are separated by a spacing s, and aratio s/w has a value ranging from 1 to 2. In some embodiments, theplate and the inductive device are part of a first unit cell, and thefilter structure includes an array of unit cells including the firstunit cell. In some embodiments, each unit cell of the array of unitcells includes the ground plane. In some embodiments, the array of unitcells is one of a 1×4 array, a 1×8 array, a 2×3 array, or a 3×3 array.In some embodiments, the inductive device is part of a powerdistribution path of the IC package.

Another aspect of this description relates to a method of forming afilter structure. The method includes forming a ground plane in a firstpost-passivation interconnect (PPI) layer of an integrated circuit (IC)package, forming a plate in a second PPI layer of the IC package,depositing a dielectric layer between the ground plane and the plate,forming an inductive device in a third PPI interconnect layer of the IC,and constructing an electrical connection between the plate and theinductive device. The forming the ground plane, the forming the plate,and the forming the dielectric layer are part of constructing acapacitive device. In some embodiments, the constructing the electricalconnection includes forming a via between the second PPI layer and thethird PPI layer. In some embodiments, the forming the plate and theforming the inductive device include forming a perimeter of the plateand a perimeter of the inductive device aligned in a directionperpendicular to a plane of the ground plane. In some embodiments, theforming the inductive device includes forming a spiral path having awidth w and a spacing s, and a ratio s/w has a value ranging from 1 to2. In some embodiments, the forming the plate is part of forming aplurality of plates, the forming the inductive device is part of forminga plurality of inductive devices, each inductive device of the pluralityof inductive devices being electrically connected to a correspondingplate of the plurality of plates, and the constructing the capacitivedevice is part of constructing a plurality of capacitive devices, eachcapacitive device of the plurality of capacitive devices including theground plane and a corresponding plate of the plurality of plates.

Still another aspect of this description relates to a method offiltering a signal. The method includes receiving an input signal at afirst terminal of a filter structure in an integrated circuit (IC)package, reducing a high frequency component of the input signal usingthe filter structure to generate an output signal, and providing theoutput signal at a second terminal of the filter structure. The filterstructure includes an inductive device in a first metal layer of the ICpackage and a capacitive device electrically connected to the inductivedevice. The capacitive device includes a first plate in a second metallayer of the IC package and a second plate in a third metal layer of theIC package. In some embodiments, receiving the input signal at the firstterminal of the filter structure includes receiving the input signal ata first terminal of the inductive device, providing the output signal atthe second terminal of the filter structure includes providing theoutput signal at a second terminal of the inductive device, and thecapacitive device is electrically connected to the inductive devicethrough a third terminal of the inductive device. In some embodiments,the filter structure includes another inductive device in the firstmetal layer of the IC package electrically connected to anothercapacitive device including the first plate and a third plate in thethird metal layer of the IC package, receiving the input signal at thefirst terminal of the filter structure includes receiving the inputsignal at a terminal of the inductive device, and providing the outputsignal at the second terminal of the filter structure includes providingthe output signal at a terminal of the another inductive device. In someembodiments, reducing the high frequency component of the input signalis based on a predetermined resonance frequency corresponding to a sizeof the inductive device and a size of the capacitive device. In someembodiments, the predetermined resonance frequency is greater than 1gigahertz (GHz).

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A filter structure comprising: a ground plane ina first metal layer of an integrated circuit (IC) package; a plate in asecond metal layer of the IC package; a dielectric layer between theground plane and the plate, the ground plane, the dielectric layer, andthe plate thereby being configured as a capacitive device; and aninductive device in a third metal layer of the IC package, wherein theinductive device is electrically connected to the plate, and theinductive device comprises two symmetrical paths electrically connectedat a center of the inductive device.
 2. The filter structure of claim 1,wherein the plate is positioned between the ground plane and theinductive device.
 3. The filter structure of claim 1, wherein aperimeter of the plate is aligned with a perimeter of the inductivedevice.
 4. The filter structure of claim 1, wherein the two symmetricalpaths comprise two symmetrical spiral paths.
 5. The filter structure ofclaim 4, wherein each path of the two symmetrical spiral paths has awidth w, the two symmetrical spiral paths are separated by a spacing s,and a ratio s/w has a value ranging from 1 to
 2. 6. The filter structureof claim 1, further comprising a via extending from the center of theinductive device to the plate.
 7. The filter structure of claim 1,wherein the plate and the inductive device are part of a first unitcell, and the filter structure comprises an array of unit cellsincluding the first unit cell.
 8. The filter structure of claim 7,wherein each unit cell of the array of unit cells includes the groundplane.
 9. The filter structure of claim 7, wherein the array of unitcells is one of a 1×4 array, a 1×8 array, a 2×3 array, or a 3×3 array.10. The filter structure of claim 1, wherein the inductive device ispart of a power distribution path of the IC package.
 11. A method offorming a filter structure, the method comprising: forming a groundplane in a first post-passivation interconnect (PPI) layer of anintegrated circuit (IC) package; forming a plate in a second PPI layerof the IC package; depositing a dielectric layer between the groundplane and the plate; forming an inductive device in a third PPI layer ofthe IC package; and constructing an electrical connection between theplate and the inductive device, wherein the forming the ground plane,the forming the plate, and the depositing the dielectric layer are partof constructing a capacitive device, and the forming the plate and theforming the inductive device include forming a perimeter of the plateand a perimeter of the inductive device aligned in a directionperpendicular to a plane of the ground plane.
 12. The method of claim11, wherein the constructing the electrical connection between the plateand the inductive device comprises constructing a via between the secondPPI layer and the third PPI layer.
 13. The method of claim 11, whereinthe forming the inductive device comprises forming a first spiral pathand a second spiral path, and the first spiral path and the secondspiral path are rotationally symmetrical spiral paths.
 14. The method ofclaim 11, wherein the forming the inductive device comprises forming aspiral path having a width w and a spacing s, and a ratio s/w has avalue ranging from 1 to
 2. 15. The method of claim 11, wherein theforming the plate is part of forming a plurality of plates, the formingthe inductive device is part of forming a plurality of inductivedevices, each inductive device of the plurality of inductive devicesbeing electrically connected to a corresponding plate of the pluralityof plates, and the constructing the capacitive device is part ofconstructing a plurality of capacitive devices, each capacitive deviceof the plurality of capacitive devices including the ground plane and acorresponding plate of the plurality of plates.
 16. A method offiltering a signal, the method comprising: receiving an input signal ata first terminal of a filter structure in an integrated circuit (IC)package; reducing a high frequency component of the input signal usingthe filter structure to generate an output signal; and providing theoutput signal at a second terminal of the filter structure, wherein thefilter structure comprises: an inductive device in a first metal layerof the IC package, the inductive device comprising two symmetrical pathselectrically connected at a center of the inductive device; and acapacitive device electrically connected to the inductive device, thecapacitive device comprising a first plate in a second metal layer ofthe IC package and a second plate in a third metal layer of the ICpackage.
 17. The method of claim 16, wherein the receiving the inputsignal at the first terminal of the filter structure comprises receivingthe input signal at a first terminal of the inductive device, theproviding the output signal at the second terminal of the filterstructure comprises providing the output signal at a second terminal ofthe inductive device, and the capacitive device is electricallyconnected to the inductive device through a third terminal at the centerof the inductive device.
 18. The method of claim 16, wherein the filterstructure further comprises another inductive device in the first metallayer of the IC package electrically connected to another capacitivedevice, the another capacitive device comprising the first plate and athird plate in the third metal layer of the IC package, the receivingthe input signal at the first terminal of the filter structure comprisesreceiving the input signal at a terminal of the inductive device, andthe providing the output signal at the second terminal of the filterstructure comprises providing the output signal at a terminal of theanother inductive device.
 19. The method of claim 16, wherein thereducing the high frequency component of the input signal comprisesreducing the high frequency component based on a predetermined resonancefrequency corresponding to a size of the inductive device and a size ofthe capacitive device.
 20. The method of claim 19, wherein thepredetermined resonance frequency is greater than 1 gigahertz (GHz).